OBJECTIVE We assessed the association between diet quality and microalbuminuria in youth-onset type 1 diabetes using three indices: a modified Mediterranean diet score for children and adolescents (mKIDMED), the Dietary Approaches to Stop Hypertension (DASH), and the Healthy Eating Index-2010 (HEI). RESEARCH DESIGN AND METHODS Youth and young adults from the SEARCH (SEARCH for Diabetes in Youth) Nutrition Ancillary Study (SNAS) diagnosed with type 1 diabetes in 2002–2008, who had repeated dietary assessments at baseline and follow-up visits and urine albumin-to-creatinine ratio (UACR) measured at the outcome visit (2012–2015) (n = 461), were selected for study. Regression models estimated the association between each longitudinally assessed diet score and UACR and microalbuminuria (UACR ≥30 μg/mg). RESULTS The cohort was 43% female, and at follow-up, mean age was 20 years, disease duration was 108 months, and 7% had microalbuminuria. Adherence to a higher-quality diet was low for the mKIDMED (mean 3.7 of a possible range of −3 to 12) and the DASH (mean 42 of 80) and better, for the HEI (mean 56.3 of 100). A borderline inverse association was observed between the HEI score and microalbuminuria after adjustment for caloric and protein intake and demographic and disease factors (odds ratio [OR]HEI 0.83, P = 0.07), which lost significance with further adjustment for HbA1c and systolic blood pressure (ORHEI 0.86, P = 0.19). Results were similar for continuous UACR. No significant associations were observed for diet quality characterized by the mKIDMED or DASH indices. CONCLUSIONS Greater adherence to the HEI may be beneficial for kidney health in youth and young adults with type 1 diabetes. Low adherence to the mKIDMED and DASH diets may explain the lack of association with microalbuminuria.